Check valves for wastewater and raw water services must be capable of passing large solids and, as with shutoff valves, must have no obstructions to catch stringy material. One of the best check valve choices to use with wastewater is flap valves, which might be used in special circumstances (for example, with combined sewers that contain storm water and wastewater).

Laminar range of flap valves models offer high corrosion resistance, low maintenance, and a variety of mounting options. Depending on application and installation, flap valves are available in high strength stainless steel or ductile iron.